Dual-polarized antennas in the field of mobile radio are preferably used at 800-1000 MHz and 1700-2200 MHz. In this case, an antenna produces two orthogonal polarizations, and, in particular, the use of two linear polarizations aligned at +45° and −45° with respect to the vertical has been proven (X polarization). In order to optimize the illumination of the supply area, antennas with different horizontal 3 dB beam widths are used with 3 dB beam widths of 65° and 90° having been implemented.
For antennas with only one polarization, there are a number of solutions in the prior art for providing these different 3 dB beam widths.
Thus, for example, simple vertically aligned dipoles with a reflector that is optimized for the appropriate 3 dB beam width are used as vertically polarized antennas. For antennas for only one operating frequency band, solutions for X-polarized antennas with 3 dB beam widths of 90° have likewise already become known. Cruciform dipoles, dipole squares or patch antenna elements with an appropriately designed reflector are used, by way of example, for this purpose, in order to achieve an appropriate horizontal 3 dB beam width.
According to DE 197 22 742 A1, a reflector geometry is proposed for this purpose in which slots are incorporated in the reflector side boundaries which project laterally beyond the reflector plate. If a reflector geometry such as this is used, for example, for cruciform dipoles or for a specific dipole structure such as that which is known by way of example from DE 198 60 121 A1, then a horizontal 3 dB beam width of between about 85° and 90° can be achieved. However, this example relates only to an antenna which is operated in only one operating frequency band.
However, in the case of dual-polarized antennas which are intended to be operated in two frequency bands that are well apart from one another and which are offset, for example, by a factor of 2:1 from one another, solutions are known only with horizontal 3 dB beam widths of about 65°.
By way of example, DE 198 23 749 in this context proposes a combination of dipole antenna elements, allowing a 3 dB beam width of about 65° to be achieved for the two frequency bands (for example the 900 MHz band and the 1800 MHz band).
A corresponding solution using patch antenna elements is known, for example, from WO 00/01032.
It has not yet generally been possible to produce antennas which can be operated in two frequency bands or in two operating frequency ranges and at the same time are intended to have a 3 dB beam width of about 90°.
Furthermore, reference is also made to further prior publications relating to antennas which, however, are likewise not suitable for operation with a 3 dB beam width of about 90° in two frequency bands that are offset with respect to one another. By way of example, these are antennas such as those described in the publication S. Maxi and Biffi Gentili: “Dual-Frequency Patch Antennas” in: IEEE Antennas and Propagation Magazine, Vol. 39, No. 6, December 1997. A dual-polarized antenna which has a triple structure and whose polarization is aligned horizontally and vertically is also known from Nobuhiro Kuga: “A Notch-Wire Composite Antenna for Polarization Diversity Reception” in IEEE AP Vol. 46, No. 6, June 1998 pages 902-906. This antenna produces an omnidirectional polar diagram. However, this does not relate to a dual-band antenna which has a horizontal 3 dB beam width of about 90°.
Exemplary illustrative non-limiting technology described herein provides an antenna element arrangement which, firstly, can be used for two orthogonal polarizations and in which at least one antenna element can be integrated for a higher frequency band range, with the aim of being able to achieve 3 dB beam widths of about 90°.
The dual-polarized antenna element arrangement according to exemplary illustrative non-limiting implementations make it possible to construct antennas which have horizontal 3 dB beam widths of 90° in both frequency bands. Independently of this, these antenna element structures may, however, also be used for operation in only one frequency band, if required.